Step tread formation



FIG. 1 is a FRONT AND LEFT SIDE PERSPECTIVE view of a step tread showing our new design;

FIG. 2 is a TOP PLAN view thereof;

FIG. 3 is a FRONT ELEVATION view thereof;

FIG. 4 is a RIGHT SIDE ELEVATION view thereof;

FIG. 5 is a LEFT SIDE ELEVATION view thereof;

FIG. 6 is a BOTTOM view thereof; and,

FIG. 7 is a REAR SIDE ELEVATION view thereof.

The break lines in the drawings indicate that the appearance of any portion of the step tread between the break lines forms no part of the claimed design. 

CLAIM The ornamental design for a step tread formation, as shown and described. 